Defining the number of options to be selected from dropdown selection html

Question

Is there a way to limit the number of options the user can select in a multiple select html field like the one below?

<select multiple id="color" name="color" size=5>
<option>- Choose one -</option>
<option value="blu">Blue</option>
<option value="yel">Yellow</option>
<option value="bla">Black</option>
<option value="ora">Orange</option>
</select>

Say I want to 'force' the user to select exactly two out of the four options. How would I do that?

Answer 1

Count them if there are more than desired unselect the extra one or do whatever you need with the list when you have already 2 selected ( like disable it )

Fiddle: http://jsfiddle.net/6kMWu/

$('#color > option').on('click', function (e) {
    var selected = ($('#color > option:selected').length);
    console.log(e.target);
    if(selected > 2)
    {
        $(e.target).removeAttr('selected');
        return false;
        e.preventDefault();
    }
});